"Squiggy" is a generic pet name for any particular "internet tough guy" who frequents your forum/message board/IRC channel/etc. The image that is brought to mind is that of a tiny dog, like a Chihuahua, who thinks that it's a Great Dane; it clamps its tiny mouth onto the cuff of your jeans and tugs at it with all its might, feet sliding comically on the floor trying to gain traction, all while growling at the top of its little doggie vocal chords. It is generally awarded to an individual (you know who) who is the most vehement defender of the most retarded ideas imaginable.